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United  States  PepnriiikMii  uf  \unViilture, 


nir  vi-i'i  i   i  BEE  tin  i  (  v  i  iiti'ii  i  vi 

i  UalticoxoMHi  ami  *  i<  una   I  'nb.  i 


/;/   Chargi 


Bj    \.  I..  Qi  u\i 
I   Deciduous   Fruit  Insert   Investigation*. 


The  conspicuous,  unsightly  nests  or  tents  of  this  insect  (fig.  -J) 
are  familiar  objects  in  the  spring  in  trees  along  roadways,  streams, 
fences  in  neglected  orchards,  and  elsewhere.  The  gregarious  cat- 
erpillars construct  the  tents  for  their  protection,  and  these,  at  lir-i 
small,  are  gradually  enlarged  as  the  larvae  grow,  often  h 
or  more  in  height  and  diameter,  the  size  varying  with  the  nu 


sin  1  i . 

of  individuals  in  the  colony.     The  caterpillars  feed  upon  the  foli 
>f  the  trees,  stripping  the  leaves  from  the  limbs  adjacent  to  the 

nest,  and  if  the  era)  colonies  in  a  ti   e,        is  frequently  the 

during  periods  of  abundant  e,  >liage  may  be  quite  d 

Leaving  the  branches  as  bare  as  in  midwinter. 


us 


DISTRIBUTION    AND   FOOD   PLANTS. 

The  tent  caterpillar  is  a  native  American  species  occurring  quite 
generally  in  the  United  State-  from  Canada  south  to  Florida  and 
westward  about  to  the  Rocky  .Mountains.  From  the  Rockies  to  the 
Sierras,  according  to  Dyar,  the  species  is  replaced  by  Malacosoma 
fragilis  Stretch,  which  range-  from  Canada  to  Mexico,  and  this  lat- 
ter form  in  the  Pacific  Northwest  is  replaced  by  Malacosoma  plu- 
vialis  Dyar. 

The  tent  caterpillar  has  been  a  troublesome  pest  from  the  earliest 
limes.  As  stated  by  Fitch,  its  injuries  in  Massachusetts  in  the 
years  L646  and  1649  led  the  early  settlers  to  term  these  "caterpillar 
years."  At  rather  long  and  irregular  intervals  the  caterpillars  have 
been  excessively  abundant  in  different  parts  of  their  range,  but  more 
particularly  in  the  New  England  States.  This  species  was  among 
the  first  to  receive  attention  by  the  early  American  entomologi-t-. 
and  the  principal  feature-  in  it-  life  and  habits  have  been  known  for 
many  years.  Throughout  its  extended  distribution  the  insect  is 
likely  to  be  abundant  each  year  in  one  or  more  localities  and  often 
over  a  considerable  territory.  Scattered  nests  are  to  be  found  usu- 
ally during  any  spring,  though  during  some  seasons  these  are  but 
little  in  evidence. 

The  favorite  food  of  the  tent  caterpillar  is  the  wild  cherry,  and 
this  is  probably  its  native  food  plant.  Next  to  the  wild  cherry  the 
apple  is  apparently  preferred.  In  the  absence  of  its  favorite  food, 
or  under  special  condition-,  it  attacks  many  other  plants,  as  plum, 
peach,  thorn,  pear.  rose,  and  other  members  of  this  group;  also 
beech,  witch-hazel,  elm.  maple,  various  species  of  willows,  oaks,  and 
poplars,  etc.  During  period-  of  unusual  abundance  trees  are  more 
or  less  completely  defoliated,  and  at  a  time  when  they  most  need  the 
leaves  for  their  growth  or  for  the  development  of  the  fruit,  and  they 
are  materially  weakened,  though  rarely  killed. 

DESCRIPTION    AND    LIFE    HISTORY. 

The  egg. — Eggs  are  deposited  in  masses  or  belts  encircling  the 
-mailer  twigs,  as  shown  in  fig.  -J.  and  at  a,  fig.  1.  Different  ^gg  masses 
may  vary  from  one-half  to  three-fourths  of  an  inch  in  length  and 
contain  from  150  to  250  eggs.  The  average  number  of  eggs  in  several 
egg  masses  counted  by  Prof.  V.  II.  Lowe  on  peach  and  apple  was 
tbout  223  each.  Each  egg  belt  i-  deposited  by  an  individual  female 
ind  ordinarily  represents  the  entire  number  which  she  will  deposit. 
Eggs  are  placed  on  end.  cemented  closely  together,  the  whole  oval- 
shaped  mass  being  finally  covered  with  a  layer  of  light-brown  frothy 
glue,  which  soon  becomes  tough,  brittle,  and  glistening. 

[Cir.  98] 


.,,.  deposited  bj  the  rnotha  bj  earl)   midsummer,  ...  earhei 
in  the  South,  the  embryonic  lar  >  thai  bj  fall  the}  are 

Dracticall3f  full  grown,  although  remaining  within  the  egg  until  the 


n,     •■  -Apple-tree  tenl  MterpUtare  i  " 

"  ..„"!!...  twig  at   left.  ne-haM   "^ 

il.) 

following  spring.    With   the  comii  warm  spell   the   larva 

escape  by  gnawing  through  their  egg  shells,  often  before  there  is 


foliage  out   for  food,  and  under  these  circumstances  they  may  feed 
upon  the  glutinous  covering  of  the  egg  mass. 

The  larva. — In  the  presence  of  food  the  larva"  begin  the  formation 
of  their  nesl  in  about  two  days  from  hatching,  usually  selecting  the 

crotch  formed  by  two  limits  and  ordinarily  one  that  is  not  far  from 
the  egg  mass.  The  caterpillars  are  sociable,  those  from  one  egg 
mass  inhabiting  one  nest  and  feeding  together  upon  the  adjacent 
leaves.  If  two  egg  masses  happen  to  be  deposited  close  together,  as 
on  the  same  or  adjacent  twigs,  the  resulting  caterpillars  may  mute 
in  one  nest.  Wherever  they  go  each  larva  spins  a  thread  of  silk,  the 
young  individuals  hanging  suspended  from  a  silken  thread  when 
they  drop,  as  do  the  cankerworms  and  many  other  larvae.  The  nests, 
at  lirst  small  and  affording  but  little  shelter,  are  gradually  enlarged 
as  the  caterpillars  grow  and  soon  furnish  ample  protection.  Upon 
(dose  examination  the  nests  of  this  species  will  he  found  to  he  made 
up  of  layers  of  silk,  with  room  for  the  larvae  between  the  layer-. 
According  to  Fitch  these  layers  are  the  resull  of  the  caterpillars" 
habit  of  lying  on  the  outside  of  the  nest  during  bright  weather,  the 
few  restless  individuals  crawling  hack  and  forth  over  the  resting 
mass,  spinning  silk  as  they  go,  soon  forming  a  new  layer.  During 
rainy  and  cloudy  weather  the  larvae  remain  mostly  within  the  nest, 
hut  when  the  weather  is  favorable  they  feed  at  regular  intervals; 
according  to  Fitch,  in  the  morning,  in  the  afternoon,  and  again -dur- 
ing the  night.  Upon  becoming  nearly  full  grown  the  larvae  wander 
singly  away  from  the  nest,  feeding  upon  such  plant-  as  come  to  hand. 
This  wandering  habit  preparatory  to  pupation  results  in  the  scatter- 
ing of  the  pupa1  and  greatly  increase-  the  chances  of  their  escape 
from  destruction  from  their  numerous  natural  enemies. 

When  full  grown  the  caterpillars  are  about  2  inches  long,  cylin- 
drical, deep  black  in  color,  with  a  white  stripe  along  the  back  and 
lateral  markings,  as  shown  in  fig.  1,  b.  On  each  side  i-  a  row  of  oval 
pale-blue  spots,  one  on  the  middle  of  each  segment,  and  on  the  ante- 
rior side  of  each  is  a  broader,  deep  velvety  black  spot.  The  body  is 
sparsely  clothed  with  fine  soft  yellowish  hair-  of  varying  length, 
thickest  perhaps  toward  the  anterior  end.  where  they  project  forward 
over  the  black-colored  head.  In  about  six  weeks  from  hatching  the 
larvae  become  full  grown  ami  wander  away  from  the  nest,  as  stated, 
in  search  of  suitable  places  for  pupation. 

The  cocoon. — The  larva1  select  for  pupation  any  convenient,  more 
or  less  secluded  place,  as  under  loose  bark,  in  grass  or  brush  under 
trees,  along  fence-,  etc.  If  close  to  outbuildings  the  larvae  often  make 
their  cocoons  in  the  angles'  along  the  sides,  in  window  casings,  etc. 
The  cocoon,  shown  at  <1.  fig.  1.  i-  oval  in  shape,  about  1  inch  lone-, 
md   composed   exteriorly  of  coarse,  loose,   whitish   threads  of  silk 

[Cir.  !>s] 


ncYmg  the  tougher   parchment-like  lining.    The   silk   of  the 
i-  intermixed  n  itli  n  yellow   powdi  tancc  which  readily 

comes  off  when  disturbed.     C i    are  made  more  or  less  singly, 

though  in  suitable  shelter  near  the  i  eral  may  be  found  spun 

together,  the  larva  taking  nd vantage  of  the  same  • 
""»ii-  are  frequentl}  found  within  the  nest,  though  these  will  usually 
l'i'"'  ••  i"  be  parasitized. 

1,1  Within  the  cocoon  the  larva  changes  to  a  short,  oval, 

brownish  pupa,  as  shown  at  c,  fig.   I.     This  stage  lasts  about   three 
ks,  the  time  varying  somew  hat  ;  then  the  moth  app< 

Both  sexes  of  the  tent  caterpillar  moth  are  shown  in 
''-•   '•  li"'  female  to  the  left.     I'  .lull  reddish  brown,  stout- 

bodied  moths,  with  a  wing  expanse  in  the  females  of  about  L.5  to  2 
■nches,  and  in  the  males  of  from  L.2  to  L.3  inches.  Obliquely  across 
the  brewings  of  each  sex  are  two  nearly  parallel  whitish  lines,  as 
shown  n.  the  illustration.  Soon  after  emergence  the  sexes  mate,  and 
lv  deposited  on  limbs  and  i     •■        I      re       b  Deration 

hyear,  the  insects  existing  in  the  egg  stage  throughout  the  remain- 

m«s mer  Mti.l  fall  and  through  the  winter,  the  voung  larva?  com- 

ing  Prom  the  eggs  in  early  spring  and  forming  their  nests,  or  tent 
stated. 

NATURAl     ENEMIES. 

This  species  is  subject  to  attack  by  numerous  parasitic  and 
daceous  enemies,  which  undoubtedly  exert  an  important  influence  in 
"'"-  »«  reduced.  Very  minute,  four-winged  flies  of  the  order 
Hymenoptera  deposit  their  eggs  within  those  of  the  tent  caterpillar 
moth,  the  resulting  larvae  or  grubs  finding  sufficient  food  for  their 
growth  and  development  to  parent  flies.  Four  egg  parasit 
been  recorded  for  this  species,  namely,  .  ipa  u\\ry. 

Pteromalvs    sp.,  Platygaster  sp.,  and    Ah  ,,,,    Ajshm.' 

the  latter  record,  however,  being  undoubtedly  incorrect,  since  this 
species  is  parasitic  upon  scale  insects. 

Larva?  and  pupae  furnish   f I   for  a  large  number  of  parasites 

and  hyperparasites.     Thus  W.  V.  Fiske     records  a  total  of  some  2J 

species  of  insects  which  directly  or  indirectly    f I  upon  the  tent 

caterpillar.     Primary  parasites  which  have  been  recorded  from  the 
larva  and  pupa  are:  Pimpla  ■    ,  •  -  .  /-. 

'"•i  S        P.  Cress.,  /'.   n  Brulle,  ApanU 

s  var-  Riley,  A.  kshm.,  I. 

Itivum    Say,    .!  nw   clvnocampa    Weed,    AnomaLi 

Prov.,  .1.  ant  '    Say,  Spilot  >■>;,  .  s  ( Jn 

Cress.,  B  V.shm.,  Diglochh  omn '  Walk., 

•Tech.  Bui.  So.  6.  \.  li.  ■  s<  ,..  ,,.  ■_.  ,  ■ 

[Clt 


Theronia  melanocephala  Brulle  (?),  and  the  dipteron  Frontina 
in  nchii  \\"\\\. 

Among  predaceous  insects  are  several  species  of  ground  beetles 
which  arc  said  to  feed  upon  the  larvae,  among  them  Calosoma  scruta- 
tor Fab.  Among  the  Hemiptera  Mr.  A.  II.  Kirkland  has  observed 
several  species  of  Podisus  attacking  the  larvae  {Podisus  placidus  DhL, 
/'.  modestus  Dall.,  and  P.  serieventris  Uhl.)  and  the  rudiviid  Di- 
plodus  luridus  Stal.  Also,  according  to  Professor  Bruner,  Podisus 
spinosus  Dall.  and  Perillus  claudus  Say  are  enemies  of  the  caterpil- 
lar-. 

While  most  birds,  as  a  rule,  do  not  feed  on  hairy  larva1,  such  a> 
the  tent  caterpillar,  yet  several  species  are  known  to  include  this 
insect  in  their  diet,  as  the  black-billed  and  yellow-billed  cuckoos,  the 
bluejay,  and.  according  to  Mr.  E.  II.  Forbush,  the  crow,  chickadee. 


Fig.  '■',. — Pimpla  conguisitor,  an  important  parasite  'of  the  tent  caterpillar:  «,  Larva, 
enlarged  ;  b,  head  of  same,  still  more  enlarged  :  <■.  pupa  :  <l .  adult  female,  enlarged  : 
<.  f.  end  of  abdomen  of  adult  male,  still  more  enlarged.  (From  Fourth  Kept.  T".  S. 
Entom.  Comm.  i 

Baltimore  oriole,  red-eyed  vireo.  chipping  sparrow,  and  yellow  war- 
bler. Kirkland  states  that  the  common  toad  feeds  greedily  on  tent 
caterpillars,  he  having  found  in  their  stomach-  the  remains  of  from 
15  to  '20,  and  in  one  instance  37  of  these  larvae. 

The  caterpillars  are  also  subject  to  destruction  by  a  bacterial  dis- 
ease, especially  when  they  become  grown  or  nearly  so.  and  sick,  slug- 
gish  individuals  may  often  be  observed  lying  outside  at  full  length 
on  the  nest.  Larvae  killed  by  this  disease  are  soft-bodied,  the  skin 
easily  rupturing  and  permitting  the  escape  of  the  liquid  decomposed 
body  contents. 

METHODS    OK    CONTROL. 

Rcmoriil  of  iisdcxs  trc<s. — As  has  been  stated,  the  unsightly  nests 
of  the  tent  caterpillars  are  especially  apt  to  be  found  on  wild  cherry, 
apple,  and  other  trees  growing  along  roadsides,  fences,  and  elsewhere. 
[Cir.  98] 


1,1  ""'  '  '  '  '     5"ch  trees  could  doubtless  be  removed  without  disad 

vantage,  and  their  removal  would  greatl)  reduce  the  n »er   of  this 

pest  l>\  le  their  favorite  food  supply. 

Collecting  the  eggs.  During  the  dormant  period  of  trees,  when 
the  leaves  are  off,  the  egg  mas  e  are  fairlj  con  picuous,  and  with  a 
lMl1''  Practice  may  be  readilj  found;  it  is  then  thai  they  should  be 
mi  ofl  Bnd  burned.     In.     infi   ted  with  larva?  during  the  earl)  pari 

".'  ''"'  .vr;,r-  "r  those  '"  the  inn liate  vicinity,  are  perhaps  more 

likely  to  be  chosen  l.\  the  parent  moth  for  the  deposition  of  her  eg 
and  such  trees  at  least  should  be  searched  if  it  is  not  practicable  to 

eftend  the  u,"'k  to  th -chard  as  a  whole.     This  work  may  som 

bined  with  pruning  to  good  advantage,  and  a  lookoul  should  be  kept 
not  < > 1 1 1 \   for  the  eggs  of  this  msec! 
but    for   the   eggs   and   cocoons   of 
"(her  injurious  species  which   pass 
the  winter  on  i  he  t  rees. 

I  BOl  riw    PHI    •   \  i  i  BP1  I  i  uts, 

N  iglecl  to  search  out  the 
masses  during  the  \n  inter  \\  ill  resull 
"i  the  appearance  of  the  larvse 
about  the  time  the  trees  are  putting 
forth  foliage.  The  nests,  at  6rs1 
small,  are  soon  so  increased  in  size 
as  to  attract  attention.  I  f  the  cater 
pillars  are  destroyed  as  soon  as  the 
small  nests  are  detected,  this  will 
prevent  further  defoliation  of  th.' 
trees,  and  the  rule  ~ln.nl. 1  be  adopted 

to  destroy  them  promptly  as  soon  as  discovered.  In  this  work  nil,.., 
oi  two  practices  may  be  resorted  to.  namely,  destruction  bv  hand  or 
with  a  torch. 

When  in  convenient  reach  the  nests  may  be  tun,  oul  with  a  brush 
mth    gloved    ll:""1     or   otherwise,   and    the    larvae   crushed    on    th, 
ground,  care  being  taken  to  destroy  any  caterpillars  which  may  have 
remained  on  the  tree. 

TIu'  use  "{  ;l   to"*  to  burn  out   th,'  nests   will  often  I...   found 
anient,  especially  when  these  occur  in  th,  higher  part-  of 

An  asbestos  torch,  such  a.  advertised  by  s Ismen,  will  I,' 

"f  on,,  may  be  made  simply  by  tying  rags  to  the  end  of  a  pole      Tip. 
asbestos  or  rags  are  saturated  with  kerosene  and   lighted  ami  the 
caterpillars  as  far  a-  possible  cremated.     Some  caterpillars,  hov 
are  likely  to  escape,  falling  from  the  nesl  upon  the  application  , 
torch.     In  using  the  torch  great  care  is  necessary  that  no  impoi 


■  h,  h,  the 


UNIVERSITY  OF  FLORIDA 


s  3  1262  09216  5454 

injury  be  done  the  tree:  it  should  not  be  used  in  burning  out  nests 
except  in  the  smaller  branches  and  twigs,  the  killing  of  which  would 
be  of  no  special  importance.     Nests  in  the  larger  limbs  should  be 

.lot roved  by  hand,  as  the  use  of  the  torch  may  kill  the  bark,  resulting 
in  permanent   injury. 

Spraying  with  arsenicals.— TevA  caterpillars  arc  readily  destroyed 
by  arsenicals  sprayed  on  foliage  of  trees  infested  by  them.'  Dr.  li 
Fernald's  careful  experiments  and  those  of  Professor  Lowe  in  deter- 
mining the  amount  of  poison  necessary  to  kill  the  caterpillars  show 
that  the  latter  are  very  sensitive  and  are  killed  in  from  two  to  three 
day-  by  the  use  of  Paris  green  at  the  rate  of  1  pound  to  300  or  100 
gallons  of  water. 

Orchards  or  trees  sprayed  with  arsenicals  in  the  spring  for  the 
codling  moth,  cahkerworms,  or  similar  insects  will  be  kept  practi- 
cally free  from  tent  caterpillars,  and  this  species  rarely  requires  at- 
tention at  the  han.K  of  the  up-to-date  commercial  fruit  grower.  It 
will  he  troublesome  in  the  scattered  trees  around  the  home  or  in  the 
small  orchard  which  is  not  regularly  sprayed.  On  such  trees  the 
nests  will  likely  he  in  evidence  every  spring,  and  during  occasional 
years  the  caterpillars  may  he  excessively  abundant,  completely  de- 
foliating the  trees. 

Even  in  the  small  home  orchard  of  a  dozen  or  more  tree-  it  will 
he  found  highly  profitable  to  adopt  a  system  of  spraying  which  will 
control  not  only  tent  caterpillars  but  such  serious  pests  as  the  codling 
moth,  cankerworms,  various  bud  and  leaf  feeding  insects,  and  will 
greatly  reduce  injury  from  the  curculio. 

Any    of  the   arsenical    insecticide-   may   he    used,   a-    Paris   green, 
Scheele's  green,  arsenate  of  lead.  etc.     The   former  two  are  used  at 
the  rate  of  1  pound  to  150  or  200  gallons  of  water,  and  the  latter  at 
the  rate  of  -2  pounds  to  50  gallons  of  water,  the  milk  of  lime  from  an 
equal  amount  b\    weight  of  stone  lime,  as  poison  used,  being  added  to 
neutralize  any  caustic  effect   of  the  arsenical  on  the  foliage.     Pref- 
erably, however,  the  poisons  should  !»e  used   in   Bordeaux  mixture, 
thus  effecting  a  combination  treatment   for  insect-  ami  fungous  dis- 
eases.    On  -tone  fruit-,  such  a-  cherry,  peach,  and  plum,  arsenicals 
are  likely  to  cause  injury  to  foliage  and  must  be  used  with  caution  if 
at  all.     On  such  tree-  the  arsenate  of  lead  i-  preferable,  a-  it  i-  1 
injurious  to  foliage,  and  on  all  tret-  -ticks  much  better.     In  spraying 
for  the  tent  caterpillar  only,  application-  should  be  made  while  the 
caterpillars  are  yet  -mall,  a-  these  succumb  more  quickly  to  poiso 
than  when  more  nearly  full  grown,  and  prompt  treatment  stops  fur- 
ther defoliation  of  the  tree-. 
Approved  : 

James  Wilson, 

Seen  tary  of  Agricultx 
Washington,  D.  ('..  December  ■/.  /."< 

OS  j 

o 


